1. Field of the Invention
The present invention relates to an apparatus and a method for manufacturing an optical disk, an apparatus and a method for recording data on the optical disk, and an apparatus and a method for reproducing data from the optical disk, as well as the optical disk. For example, the present invention can apply to a compact disk, a compact disk player, an optical disk for recording audio data, and a recording apparatus and a reproducing apparatus usable for the optical disk.
The present invention changes the reflectance of the optical disk locally, thereby giving a jitter to the positional information of each pit edge, so that desired data is recorded on the optical disk additionally. Consequently, various data can be recorded on the optical disk so as to be reproduced by an optical pickup for reproducing data strings and not to be copied illegally without any adverse effect on the reproduction of the data strings recorded in the from of pit strings.
In addition, the present invention deviates bits, etc. towards the inner/outer region of the optical disk, thereby recording such sub-data as key information, etc., so that various data can be recorded on the optical disk so as to be reproduced by an optical pickup for reproducing the data strings and not to be copied illegally without any adverse effect on the reproduction of the data strings recorded in the form of pit strings.
2. Description of the Related Art
In the case of conventional compact disks (CD), data strings to be recorded have been processed, then subjected to EFM modulation (Eight to Fourteen Modulation), thereby such data as audio data is recorded.
On the other hand, a management data recording area is formed in the lead-in area provided in the inner region of the optical disk and the TOC (Table Of Contents) recorded in this recording area is used to selectively reproduce desired musical performance data, etc.
A compact disk having various recorded data as described above is provided with a recording area for the IFPI (International Federation of the Photographic Industry) code in an inner area of the lead-in area, where such signals as audio signals and the TOC (Table Of Contents) used by the object user are recorded. This area also has such inscription codes as factory name, the disk number, etc., with which the history of the compact disk can be checked visually.
By the way, such the inscription data as a maker name, a factory name, a disk number, etc. are enscrolled on each compact disk so that the history of the compact disk is checked visually and such the inscription data is used for discriminating illegally copied disks manufactured from an original disk. However, because such the inscription data is recorded so as to be checked visually, the inscription data arises a problem that the data cannot be reproduced easily by an optical pickup of the compact disk player. In order to solve this problem, therefore, a reproducing mechanism is required dedicatedly for reproducing the inscription data while it is enabled to discriminate this inscription data from illegally copied disks.
The inscription data to be recorded with those methods is recorded in the form of pits ordinarily and checked visually, if it can be duplicated by, for example, creating a stamper by peeling both protection film and aluminum reflection film from the object compact disk. And, this is why the compact disk cannot be protected from illegal copying.
To solve the above-mentioned problems, for example, Japanese Patent Laid-Open No.9-67843 discloses a method in which the output of a recording laser is varied to change the pit width recorded on the disk, thereby recording the inherent code on the disk.
For example, as the first example, there is a well-known method in which a recording signal on a disk is encrypted and key information for decryption is recorded as a variation of the pit width according to the method described in the above-mentioned patent application. A reproducing apparatus is composed so that the key information recorded as described above is detected and the cryptogram is decrypted according to the detected key information. Because the key information is not recorded on the pirated disk, the cryptogram is therefore not decrypted and the content of the disk is not reproduced normally. Therefore, if a reproducing apparatus is composed as described above, then the pirated disk becomes useless, thereby the pirated copy is substantially prevented.
Now, there are two well-known methods for making a pirated disk; a method in which reproduced signal from a disk is supplied to a recording unit as is and the other method in which the physical configuration of a disk is transferred as is. If a disk which is manufactured according to the above-mentioned first example is used for making a pirated disk according to the method in which the reproduced signal is supplied to a recording unit as is, then the key information recorded in the form of pit width change is not recorded on the pirated disk though the information recorded in the form of “pit/no pit” change is recorded in the pirated disk. Therefore it is possible to prevent making of a pirated disk according to the method in which the reproduced signal is supplied to a recording unit as is by employing the method described in the first example. However, if a disk which is manufactured according the above-mentioned first example is used for making a pirated disk according to the method in which the physical configuration of a disk is transferred, then the key information recorded in the form of pit width change is also copied to a pirated disk. Therefore, the first example method is disadvantageous in that making of a pirated disk according to physical transfer can not be prevented.
Now, the second example is known as a method for solving such a problem. In the second example, the key information is recorded not in the form of physical configuration but in the form of reflectance change. In detail, a groove is formed on an area such as the lead-out area of an optical disk, an intensive laser beam is irradiated onto the reflection film of this area, thereby changing the reflection characteristic, and the same information as that of a bit string is recorded.
If the key information is recorded in the form of reflectance change, the key information is recorded in the form of reflection characteristic change of a reflection film. Because the key information is not recorded in the form of physical configuration (pit), the key information will not be copied on the pirated disk which is made according to physical transfer. Therefore, this method complements the disadvantage of the first example, and it is possible to prevent the making of the pirated disk by the use of the method according to physical transfer.
However, the second example is also disadvantageous in that if a pirated disk is made according to the method in which the reproduced signal is supplied to a recording unit as is, the key information recorded on the lead-out area is copied as is.
As described above, the respective methods for preventing the pirated disk which is proposed are effective only on either of the two methods for making a pirated disk herein addressed. Furthermore, if a pirated optical disk is made according to a method not described above, these methods are entirely not effective.
Under such the circumstances, it is an object of the present invention to provide an apparatus and a method for manufacturing an optical disk from which no pirated optical disk can be produced by any of a method in which the reproduced signal is supplied directly to a recording unit and a method in which the configuration of the optical disk is transferred physically, thereby eliminating the disadvantage of the conventional pirated copying method, and an optical disk to which such pirated copy prevention is applied and a method for reproducing an optical disk to which such pirated copy prevention is applied.
Besides that, it will also be possible to reject an illegal copy with the use of this data if various data can be recorded so as to be reproduced with an optical pickup for reproducing audio data and to be difficult to copy illegally without any adverse effect on the reproduction of audio data as pit strings.